Oil sump ventilation



Sept. 5, 1944.

E. H. KELLEY OIL SUMP VENTILATION Filed April 2 9, 1943 ig/Q2276 Patented Sept. 1944 OIL SUMP VENTILATION Edward H. Kelley, Bufialo, N. Y., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application April 29, 1943, Serial No. 485,083

5 Claims.

.This invention relates to aircraft engines and has particularly to do with the ventilation of the oil sump, or the equalization of pressure in the oil sump, the crankcase chamber, and the timing gear chamber.

In aircraft engines, particularly aircraft engines of the Pratt & Whitney type, the oil sump is positioned at the bottom of the engine below the crankcase and the timing gear chamber, and an oil drain is provided from each chamber tothe sump. It has been customary to provideopenings in the wall between the two chambers in order to equalize the air pressure, but it has been found that these openings areinsuflicient and "that the pressure from the crankcase chamber is transmitted through the crankcase drain and the oil sump into the drain from the timing gear *chamber and the constant flow of air will prevent the oil from draining down from the timing gear chamber into the oil sump. The air-pressure will continue to back up the oil and eventu- V ally force it out of the ventilation pipe for the 1 timing gear chamber at the top of the engine.

parts throw the air outwardly and produce an area of high pressure at the inside wall of the crankcase, and this higher pressure in the crank case is the cause of backing up the oil in the timing gear chamber.

It was thought that the trouble would be removed if the lower end of the drain tube from the timing gear chamber were placed far enough down in the sump so that its end would be below the level of the oil in the sump and thereby prevent the passage of air up the timing gear chamber drain. This apparent solution was unsatisfactory because the higher air pressure from the crankcase caused the oil to be forced up the timing gear chamber drain.

To overcome the difiiculty, an air relief conduit or passage was placed in the timing gear cham-. ber drain. The conduit was so positioned that its entrance opening would be above the oil level in the sump, and its exit would be .in the timing gear chamber above the entrance to the timing gear chamber drain. This passage or conduit will allow the air in the sump to pass to the timing gear chamber without affecting the drainage of oil into the sump or without backing up the oil which normally drains into the sump. The application of the conduit has produced an equalization of pressure in the sump, the crankcase and timing gear chamber, and avoided the loss of oil due to the escape or overflow of oil at the timing gear chamber ventilation opening.

On the drawing: I

Figure 1 is a sectional view through the oil sump and a part of the crankcase and timing gear chamber of a Pratt & Whitney aircraft engine.

Figures 2 and 3 are sections on the corresponding lines of Figure 1.

Referringto the drawing, 2 indicates a Pratt 8:

Whitney aircraft engine as a whole. The engine has the crankcase chamber 4 and the timing gear chamber '6. The usual counterweighted crankshaft (not shown) ismounted to rotate in the chamber 4 and the usual timing gear mechanism (not shown) operates in the chamber 6. The oil sump 8 is secured to the bottom of the engine by means of bolts or cap screws 9. An oil drain'in the form of a tube I!) is positioned in an opening I2 in the bottom of the crankcase and delivers in the sump 8' through an opening I4 therein above the level l6 of the oil therein. A second tubular oil drain I8 is positioned in an opening 20 in the timing-gear chamber and delivers into the sump 8 through an opening 22 therein, The end 24 of the drain I8 is below the normal level iii of the oil in the sump 8.

A third tube 26 extends into the sump 8. This I tube is connected to passages 28 and 30 which lead to the usual oil pump (not shown) which withdraws the oil from the sump and returns the oil to the storage'tank. A circular screen 32 is placed over the inlet 34 to the tube 26. The sump has the usual drain plug 36. 9 Referring'to the'tube or drain [0, it will be seen that it is screwed into the opening 12 and extend-s through a ring 38, fitting into the opening 14. A coil spring 40 is compressed between the ring 38 and a flange 42 on the drain ID. The pressure of the spring compresses a packing 44 between the ring 38 and a shoulder in the openme Hi.

The drain I8 comprises an upper tube 46 screwed into the opening 20 and passes through the opening 22. A ring 48 fits around the tube 46 and a compressed coil spring 50 is confined between the ring 48 and a flange 52 on the tube 46. A lower tube 54 surrounds the lower end of the upper tube 46 and this lower tube has a flared upper end 56 which rests on a shoulder in the opening 22. A packing 58 is positioned in the opening 22 over the end 56 and the pressure of the spring 50 compresses the packing.

In order to equalize the pressure in chambers 4 and 6, it has been found that openings in the intervening wall are inadequate. An opening is shown at 60 positioned in the upper part of the intervening wall 61 well beyond the upper part 10 of the conduit 62,

Equalization of pressure is obtained by mean of a conduit or tube 62 positioned inside the drain [8. The lower tube 54 of the drain has an opening 64 above the oil level [6 and the end or mouth 66 of the conduit is received in this opening. The edge of the opening is countersunk so that the end 66 will not project beyond the periphery of the tube 54. Welding or soldering at 68 rigidly connects the end 66 in the opening.

The conduit 62 extends upwardly in the drain I8 and the upper end I extends well beyond the top of the drain and into the timing gear chamber 6. The end 10 can be curved as shown in Figure l, or may be straight, as desired.

A C-shaped washer or retainer 12 is welded or soldered as at 14 to the conduit 62 and this retainer fits with a frictional engagement in the upper part of the tube 46 to support and retain the conduit 62. As will be seen in Figure 1, the conduit 62 will enable air .from the region of higher pressure in the sump 8 (and in the crankcase 4) to pass into the timing gear chamber 6, or region of lower pressure, but will not interfere "with the drainage of oil down the drain I8.

I claim:

1. In a ventilating system for the oil sump of aircraft engines having a crankcase chamber and .:a timing gear chamber, said sump being located below the chambers, the air pressure in the crankcase chamber being greater than the air pressure in the timing gear chamber, an oil drain from the crankcase chamber into the sump, an oil drain from the timing gear chamber into the sump, the lower end of said timing gear chamber drain being below the level of the oil in the sump to prevent the airpressure of the crankcase chamber from being directly exerted in the timing gear chamber drain, and a conduit in said timing gear chamber drain connecting the oil sump above the level of the oil therein with the timing gear chamber to equalize the air pressure in the two chambers.

2. Ina ventilating system for the oil sump of aircraft engines having a. crankcase chamber and a timing gear chamber, said sump being located below the chambers, the air pressure in the crankcase chamber being greater than the air pressure in the timing gear chamber, an oil drain from the crankcase chamber into the sump, an

oil drain from the timing gear chamber into the sump, the lower end of said timing gear chamber drain being below the level of the oil in the sump to prevent the air pressure of the crankcase chamber from being directly exerted in the timing gear chamber drain, and a conduit connecting the oil sump above the level of the oil therein with the timing gear chamber to equalize the air pressure in the two chambers.

3. In a ventilating system for the oil sump of aircraft engines having a crankcase chamber and a timing gear chamber, said sump being located below the chambers, the air pressure in the crankcase chamber being greater than the air pressure in the timing gear chamber, an oil drain rom the crankcase chamber into the sump, an oil drain from the timing gear chamber into the sump, the lower end of said timing gear chamber drain being below the level of the oil in the sump to prevent the air pressure of the crankcase chamber from being directly exerted in the timing gear chamber drain, a conduit in said timing gear chamber drain connecting the oil sump above the level of the oil therein with the timing gear chamber to equalize the air pressure in the two chambers, and a support for said conduit at the upper part of said drain from the timing gear chamber.

4. In a ventilating system for the oil sump of aircraft engines having a crankcase chamber and a timing gear chamber, said sump being located below the chambers, the air pressure in the crankcase chamber being greater than the air pressure in the timing gear chamber, an oil drain from the crankcase chamber into the sump, an oil drain from the timing gear chamber into the sump, the lower end of said timing gear chamber drain being below the level of the oil in the sump to prevent the air pressure of the crankcase chamber from being directly exerted in the timing gear chamber drain, an opening in the second mentioned drain above the level of the oil in the sump, and a conduit connected to the opening, said conduit extending upwardly in the drain into the timing gear chamber to equalize the air pressure in the two chambers.

5. In a ventilating system for the oil sump of aircraft engines having a crankcase chamber and a timing gear chamber, said sump being located below the chambers, the air pressure in the crankcase chamber being greater than the air pressurein the timing gear chamber, an oil drain from the crankcase chamber into the sump, an oil drain from the timing gear chamber into the sump, the lower end of said timing gear chamber drain being below the level of the oil in the sump to prevent the air pressure of the crankcase chamber from being directly exerted in the timing gear chamber drain, an opening in the second mentioned drain above the level of the oil in the sump, a conduit connected to the opening, said conduit extending upwardly in the drain into the timing gear chamber to equalize the air pressure in the two chambers, and means to support the upper end of the conduit.

EDWARD H. KELLEY. 

